The present invention is related to a chemical injector, and more specifically to a system for inducing chemical treatment of a fluid stream, such as dechlorination of water, and introduction of the chemical into a fluid stream without diverting the direction of flow of the fluid stream itself.
Dechlorination of water from the pipes of a residential development is presented as an illustrative application of the present device and method. In such development sites, newly-installed pipes are treated with chlorinated water. The chlorinated water must be removed from the pipes before normal water may be flowed therethrough for conventional residential use.
Typically, environmental regulations prohibit pumping out chlorinated water onto the ground, where it would be absorbed into the soil. Similarly, it is undesirable for chlorinated water to be pumped out into the street for removal via storm drains, as such drained water and chlorine would then contaminate lakes, ponds, streams and other water run-off sites. Accordingly, the need remains for a method for efficiently neutralizing chlorine in the water.
Common chlorine-neutralizing substances include ascorbic acid and sodium bisulfate, (NaHSO4). Sodium bisulfate is a relatively expensive neutralizing compound and its use in chlorinated water treatment is preferably optimized to consume no more sodium bisulfate than is necessary for the neutralization. Additionally, byproducts of the chlorine-neutralizing substances may themselves be subject to environmental regulations. For this reason, it is desirable that waste water contain as low a concentration of the chlorine-neutralizing substance as possible.
In other applications wherein a selected amount of chemical is to be introduced into a particular volume of fluid, a system may be employed which introduces chemical at a steady rate, irrespective of fluctuations in fluid stream flow rate. This chemical introduction scheme is effective because importance is placed on the final concentration of chemical in the fluid. Where aliquots are to be taken from the stream during chemical introduction, it becomes critical that the chemical concentration remain constant at any point in the fluid stream. An example of such applications include, e.g., liquid-state pharmaceutical manufacturing wherein chemical is injected into a fluid stream and the mixture portioned flow-wise into containers for market. Similarly, in agricultural pesticide injection into irrigation fluid flowed to a crop site for application thereto, it is desirable that a particular concentration of pesticide be applied per volume of irrigation water. As well, constant chemical introduction rate systems are inadequate when it is desired that the chemical injection rate be dynamically adjustable (e.g., dechlorination of water, wherein chlorination decreases during the dechlorination process and the rate of neutralizing chemical injection must be correspondingly reduced).
The present invention is intended to overcome these problems and limitations of the prior art.
Generally, the present invention provides an apparatus for introducing a chemical into a fluid stream, comprising a chemical injector adapted to be interposed within the path of the fluid stream flowing from an upstream conduit to a downstream conduit. The chemical injector includes a primary channel and one or more secondary channels running the length of the conduit in substantially parallel relation to the path of fluid flow through the upstream conduit. The injector further includes a first chemical feed channel, having an input end adapted to be in communication with a source of the chemical to be introduced into the fluid stream, and an output end, coupled at an oblique angle to the first secondary channel of the chemical injector.
Another aspect of the present invention is a method for introducing a chemical into a fluid stream, comprising directing a fluid stream through an upstream conduit. The fluid stream is divided into a primary flow and a substantially parallel secondary flow. A chemical source is coupled at an oblique angle to the secondary flow, and fluid flow pressure is increased until flow from the chemical source into the secondary flow is induced by vacuum pressure. The primary flow and the secondary flow are then directed into the downstream conduit.